Hydrogenation of organic compounds

ABSTRACT

Novel hydrogenation catalysts are formed by impregnating a suitable support material with an aqueous solution of a salt of a transition metal; heat-treating the impregnated support at a temperature above 500° F. to form chemical complexes on the surface of the support and to drive off moisture and absorbed oxygen; activating the surface complex by contacting the impregnated support with a soluble crganometallic compound wherein the metal constituent is selected from Groups I, II and III of the Periodic Chart of the Elements, and thereafter treating the activated support material in the presence of a gaseous stream containing hydrogen at a temperature of at least 300° F. to form a highly stable heterogeneous catalyst. The novel supported catalysts of the instant invention have been found to be highly active for the hydrogenation of organic compounds under extremely mild conditions.

CROSS-REFERENCE TO RELATED APPLICATION

This is a division of application Ser. No. 596,584, filed 7/17/75, nowU.S. Pat. No. 3,978,149, which in turn is a division of Ser. No.499,793, filed 8/22/74, now U.S. Pat. No. 3,932,547, which in turn is adivision of Ser. No. 253,765, filed 5/16/72 now U.S. Pat. No. 3,855,324,which in turn is a continuation-in-part of Ser. No. 880,933, filed11/28/69 now U.S. Pat. No. 3,711,423, which in turn is acontinuation-in-part of Ser. No. 674,098, filed 10/10/67 now abandoned.

BACKGROUND OF THE INVENTION

This invention relates to a new and useful process for the preparationof high activity catalysts suitable for reactions between hydrogen andhydrocarbons and particularly for the hydrogenation, or hydrogenaddition, to organic compounds containing nitrile groups, carbonylgroups, aromatic, acetylenic or olefinic linkages. It is also concernedwith the novel catalysts so produced, as well as the processes for usingthese catalysts.

DESCRIPTION OF THE PRIOR ART

Various heavy metals, especially transition metals, have been previouslydescribed as useful for conducting catalytic reactions. Hydrogenationcatalysts have included solid metals, slurries of metals, and metalsdispersed on supports. Solid metal catalyst had been prepared bycontacting oxides of the desired metal with reducing gases, e.g., carbonmonoxide, or hydrogen, or both. Slurries suitable as catalyst have beenprepared by contacting anhydrous solutions of organometallic compoundsof the desired metal with organoaluminum compounds, these being broughttogether to form slurried catalysts. Metals have been provided onsupports by impregnation of support with anhydrous solutions of thesalts of the desired metal, this being found by reduction of the saltsto produce deposition of metallic metal.

In Canadian Pat. No. 697,780, which issued Nov. 10, 1964, methods aredescribed for improving the activity of cobalt and for convertingcertain inactive metals, i.e., manganese and molybdenum, into activehydrogenation catalysts. In typical reactions, slurried catalyticmixtures are produced by forming anhydrous solutions of soaps of thedesired metal, and the desired organometallic reducing agent, and thencontacting the two solutions together to form catalytic reactionmixtures. In accordance with one of the methods, a support isimpregnated by contact with anhydrous or nonaqueous solution of a soapof the desired metal, and with an organometallic reducing agent, such asorganoaluminum compound, to produce a loosely supported reaction productmixture of dispersed metals. In other techniques, supports areimpregnated with soaps of the desired metal, and the support thencontacted with a solution of the organometallic reducing agent toproduce supported catalytic mixtures.

While these catalysts are moderately active hydrogenation catalysts,there are nonetheless a number of disadvantages associated with theiruse. For one thing, the materials, in all the phases of their use arehighly pyrophoric and the slurries must be formed in an oxygen-freeatmosphere. Also, the catalytic materials formed are highly pyrophoric.Thus, the catalytic product of the reaction is an insoluble pyrophoricsolid which is highly reactive whether in slurry or supported form.Moreover, the material used in forming the catalysts are quiteexpensive, to say nothing of the cost involved, due to the extraprecautions which must be taken in handling the materials. Furthermore,the organic solvents which are used are highly flammable.

In U.S. Pat. No. 3,415,759 there is disclosed a method for preparing ahydrogenation catalyst by depositing cobalt carboxylate on adiatomaceous earth support and heating the supported cobalt carboxylateat a temperature between about 135° and 160° C. and thereafter reactingthe thus heat-treated product with an aluminum alkyl. However, whentemperatures materially above about 160° C. are employed to dry thecatalysts, the catalyst becomes progressively deactivated, particularlyinsofar as the hydrogenation of high molecular weight compounds areconcerned.

SUMMARY OF THE INVENTION

It has now been discovered that novel hydrogenation catalysts exhibitingunusually high activity and stability may be prepared by impregnating asuitable support material, as hereinafter defined, with an aqueoussolution of a salt of a transition metal; heat-treating the impregnatedsupport at a temperature of at least about 500° F. to form chemicalconplexes on the surface of the support and to drive off moisture andabsorbed oxygen; activating the surface complex by contacting theimpregnated supports with a soluble organometallic compound wherein themetal constituent is selected from Groups I, II and III of the PeriodicChart of the Elements, and thereafter treating the activated supportmaterial in the presence of a gaseous stream containing hydrogen at atemperature of at least 300° F. The present invention is based on thediscovery that a highly tenaceous chemical bonding can be formed betweenthe surface of certain types of supports and the transition metals andthe metallic constituent of the soluble organometallic compound when themetals are applied to the supports under the sequence and criticallydefined conditions of the instant invention. In the sequence of processsteps, a supporting material having a surface area of at least 5 squaremeters per gram and containing at least 0.1 millimoles of hydroxylgroups per gram of support is first impregnated with a water-solublespecies of a transition metal, preferably a Group IB, IVB, VB, VIB, VIIBor Group VIII metal. Water has been found particularly suitable for theapplication of the Group IB, IVB, VB, VIB, VIIB or Group VIII metals tothe support by contacting or immersing the support in an aqueoussolution of a salt of the desired metal. Suitably, the support isimpregnated with from about 0.1 to about 20% metal, and preferably fromabout 2 to about 10% metal, based on the total weight of the depositedmetal and support.

The impregnated support is then preconditioned by heating theimpregnated support at a temperature of at least about 500° F. in orderto drive off moisture and absorbed oxygen from the catalyst surface. Thepreconditioned catalyst is then activated by contacting the impregnatedsupports with a soluble organometallic compound wherein the metallicconstituent is selected from Groups I, II and III of the Periodic Chartof the Elements and wherein the metallic constituent has an atomicnumber of from 3 to 50. Preferably, the organic constituents of theorganometallic compound are alkyl groups, particularly linear alkylgroups having from 1 to about 12 carbon atoms. Only the organometalliccompounds of Groups I, II and III which are soluble in hydrocarbons orsoluble in, or complex with ethers are suitable for the method of thisinvention. These are the organometallic species which are characterizedby predominantly covalent bonding between the metal and the alkyl and/orhydride groups. The preferred metallic constituent of the organometalliccompound is aluminum.

Thereafter, the activated supported material is treated by heating theactivated supported material at a temperature of at least 300° F. in thepresence of a gaseous stream containing hydrogen. Preferably, theactivated supported material is treated in the presence of hydrogen at atemperature above 800° F. and more preferably at a temperature in therange of from about 800° to about 1200° F. for a period of time in therange of from about 1 to about 100 hours. Surprisingly, it has beenfound that under these high severity conditions, i.e. treating theactivated supported catalyst at a temperature above 800° and up to about1200° F. in the presence of hydrogen, the activity of these catalysts isnot significantly decreased and, in fact, generally increases as thetreating severity is increased.

While the exact nature of the mechanism is not known and, though theapplicants do not wish to be bound by a specific theory on mechanism,there are certain things which are known to occur in the formation ofthese catalysts. When a suitable support has been impregnated with atransition metal and heat-treated at a temperature of at least 500° F.,there is believed to exist a chemical bonding between the surface of thesupport and the species of the transition metal. This interaction isbelieved to occur between the acid sites on the support surface and thetransition metal salt. Evidence of such interaction is obtained when,for example, iron is employed as the transition metal and is impregnatedon a suitable support and heat-treated at a temperature of 500° F. inaccordance with the practice of the instant invention, and examined byMossbauer spectroscopy. Such an examination reveals that essentially alli.e. 99+% of the iron is in the +3 valence state and the Mossbauerpattern corresponds to no known oxide of iron nor to the iron saltemployed in impregnating the suitable supporting material. Consequently,this interaction or chemical bonding between the support and thetransition metal is believed to be responsible for the difficulty inreducing such a supported catalyst to metallic iron by treatment withhydrogen. For example, under conditions of 1 atmosphere hydrogenpressure at a temperature of about 1000° F., virtually all the iron isreduced to the +2 valence state, i.e. an inactive catalyst while littleor no metallic iron is formed.

However, when the heat-treated impregnated support is treated with anexcess organometallic compound, for example, triethylaluminum, it isbelieved that the bond between the iron and the support is reduced bythe organometallic compound with the organometallic, i.e. metal alkylfragment being bonded to the support and replacing the reduced iron.Consequently, when the activated supported catalyst is then treated inthe presence of hydrogen under increasingly severe conditions, tworeactions are believed to occur: (1) further reduction of the transitionmetal species to a lower valence species or to the "nascent metal"state, and (2) simultaneous removal of the functional groups, i.e. alkyland hydride groups, from the metal alkyl fragments resulting in bondingbetween the alkyl metal and the transition metal. The abovedescribedreactions can be visualized as follows: ##STR1## wherein M-X representsthe transition metal salt impregnated upon a suitable support, ashereinafter defined, by aqueous solution; M thus representing thetransition metal; where Q represents a Group I, II or III metal and Rrepresents hydride or the organic constituent of the organometalliccompound and wherein n is equal to the valence state of Q.

The free radical Ro resulting from equation (2) must stabilize itself bycombination or disproportionation. When R is an ethyl radical, thecombination product is n-butane and the disproportionation products areethylene plus ethane. The gas liberated when these catalysts are treatedwith an organometallic compound, i.e. triethyl aluminum is predominantlyethane but containing appreciable amounts of ethylene and n-butane.Evidence for reactions (4) and (5) has been obtained by treating typicalgamma alumina supports with triethyl aluminum (no transition metalpresent) and analyzing the gases liberated when the treated alumina isheated at temperatures of 400°-1200° F. Reaction (6) represents bondingbetween a radical resulting from thermal decomposition of the Q metalhydride and an electron (probably a d-electron) supplied by thetransition metal in a reduced valence state.

While the exact nature of this bonding is unknown, it is believed thatthe product of reaction (6) which is believed to be a closeapproximation to the active sites of these catalysts, is a stable bondwhich accounts for the increased activity and inhibition of crystallitegrowth on the surface of the catalyst when the catalysts are subjectedto high temperatures in the presence of hydrogen. Closely relatedconfigurations such as: ##STR2## can easily be formed from the productof reaction (5) to give the iron a +2 valence state which has beenobserved in several cases for these catalyst systems by Mossbauer andmagnetic susceptibility. As disclosed above, a critical feature of theinstant invention is the conditions under which the activated supportedcatalyst is treated with a gaseous stream containing hydrogen. In termsof the mechanism disclosed above, this "fixation" treatment is believedto favor the completion of reactions (3), (4), (5) and (6). In thismanner catalysts several orders of magnitude more active and more stablethan those described in prior art processes are obtained.

Thus, it is believed that the applicants have discovered a new route toa valuable and novel heterogeneous catalyst which is believed to involvechemical bonding between the support, transition metal and metallicconstituent of the organometallic reducing agent which allows for ahighly active catalyst which is stable under high severity conditions.

The selection of a suitable support material upon which the transitionmetal is impregnated is an essential feature of the instant invention.Suitable supports are those having a reasonable surface area and asufficient concentration of hydroxyl groups on the surface, whichhydroxyl groups are capable of reacting with an organometallic compound,i.e. QR_(n) or QR_(n) X_(n), where Q represents a Group I, II or IIImetal, R represents hydride or an organic constituent, e.g. an alkylgroup of the organometallic compound, and wherein X equals a halogen, inorder to eliminate the RH species and attach the QR_(n-1) species tosupport surface through the oxygen atom of the original hydroxyl group.Properties and suitability of supports can be characterized in terms ofsurface area and their hydroxyl content measured by reaction with anorganometallic i.e. QR_(n) compound in the absence of a transitionmetal.

Those supports most suited to the instant invention include the oxidesof Groups II, III and IV of the Periodic Chart of the Elements which canbe prepared with surface areas in excess of 5 square meters per gram andwherein the hydroxyl content of the support is at least 0.1 millimolesof hydroxyl groups per gram of support. The oxides of Groups II, III andIV having a surface area in excess of 50 square meters per gram andcontaining a hydroxyl group content of at least 0.2 millimoles ofhydroxyl groups per gram of support, determined by reaction of thesupport with the organometallic compound in the absence of thetransition metal are preferred. Aluminum oxide having a surface area ofabove about 100 square meters per gram and a hydroxyl content of atleast 1 millimole per gram is the most preferred supporting material ofthe instant invention. Additional, nonlimiting examples of suitablesupporting materials include magnesium oxide, zinc oxide, titaniumoxide, provided they have the necessary surface areas and reactivehydroxyl group content as described above. Any types of supports, whilepossessing the desired surface area, may or may not have the desiredreactive hydroxyl group content. Nevertheless, some such supports, forexample, activated carbon, can be enhanced in hydroxyl group content bytreatment with air or an air-steam mixture at moderate temperatures,i.e. below about 1000° F. in order to form a suitable support for thecatalyst of the instant invention. Other well-known supports, such assilica, have a sufficient surface area but may lack the necessaryconcentration of reactive hydroxyl groups and are not suitable.Silica-alumina supports, having the necessary hydroxyl groupconcentrations are effective supports and may also be employed in thepractice of the invention.

The supported catalyst of the instant invention may be prepared by anymeans conventionally used for the preparation of a supported catalyst,e.g. by impregnating the support or by precipitation in the presence ofthe support or by coprecipitation with the supporting material. Waterhas been found to be particularly suitable for the application of thetransition metal salt to the supporting materials. Preferably, thesupport is first impregnated with a water-soluble species of thetransition metal salt by contacting or immersing the support in anaqueous solution of the salt of the desired metal. Preferably, thesupport is impregnated with from about 0.1 to about 30% equivalenttransition metals; and preferably from about 1 to about 10% equivalenttransition metal, based on the total weight of the deposited equivalentmetal and support. The optimum concentration of transition metal on thesupport will depend on the nature of the transition metal and on thesurface area and hydroxyl content of the support. For example, when apure activated alumina having a surface area of about 200 square metersper gram and a hydroxyl content of about 1.2 millimoles per gram isemployed as the supporting material, and when iron is employed as thetransition metal, the optimum concentration of iron is about 0.6millimoles of iron per gram support. With noble metals, for example muchlower concentration in the range of 0.1 to 1% are employed. The optimumconcentration for other transition metals which results in the highlyactive, stable catalysts of the instant invention are not known withexactitude because of the many and varied supports which can be employedherein. Nevertheless, it is believed that one skilled in the art canreadily determine these concentrations in view of the fact that they arewithin the preferred concentration ranges as described above.

The use of water to effect the chemical bonding is particularlyimportant in the impregnation of the supports with salts of the desiredtransition metal. Even iron has produced an exceptionally activecatalyst when applied to the support in the form of salts dissolved inaqueous solution. In fact, catalyst derived from aqueous solutions ofiron salts have ever proved highly effective for the hydrogenation ofaromatic nucleus and carbonyl groups of organic compound, i.e. aldehydesand ketones.

The transition metals which can be employed in the practice of theinstant invention include the Groups IB, IVB, VB, VIB, VIIB and GroupVIII metals. Preferably, the transition metals which can be employed inthe practice of the instant invention include iron, cobalt, nickel,platinum, tungsten, chromiun, vanadium, molybdenum, rhenium, manganese,titanium, zirconium, palladium, rhodium, copper, silver and gold. Themost preferred transition metals include iron, cobalt and nickel,platinum, tungsten, chromium, molybdenum, vanadium, rhenium and copper.Nonlimiting examples of salts which can be employed for the applicationof these metals to these supports include the halides, sulfates,nitrates, formates, acetates, propionates, molybdate, vanadates,chromates, dichromates, tungstates, manganates, titanates, zirconates,rhenates, perhenates and the like. Water soluble acids such as perrhenicacid may also be employed. These various transition metals describedabove may be used alone or in combination.

The impregnated support in powder or granular form, is then treated byestablishing time-temperature relationships suitable to produce achemical change on the surface of the support and remove water andabsorbed oxygen. Suitably, the impregnated support can be heated in air,in an inert atmosphere or in vacuum, e.g. 20 to 29 inches of vacuum at atemperature of at least about 500° F. preferably 600° to 1500° F. andmore preferably from about 600° to about 1000° F. It is a criticalfeature, in order to form the more highly active and stable catalyst ofthe instant invention, to heat the impregnated support at a temperatureabove 500° F. for a period of time in the range of about 0.5 to about 4hours and preferably from about 1 to 2 hours. While the heat-treatmentmay be performed in air or an oxygen atmosphere, it must then befollowed by a period of an inert atmosphere in order to remove theadsorbed oxygen. In addition to the removal of oxygen and moisture,other important reactions occur during this heat-treatment, as describedabove, in order to render the transition metal in a form more amenableto the subsequent reaction with the organometallic compounds.

In an alternative embodiment, the impregnation and heat-treating stepscan be conducted in multiple stages. For example, the support can beimpregnated and then dried or partially dried, at low temperature. Thesupport can then be reimpregnated and again dried or partially dried.The heat treatment per se may be conducted in multiple stages, ifdesired. The impregnated support, to facilitate handling, can thus besubjected to a first rather mild heat treatment to dry the support andthen, in a second step, to a more severe treatment to produce thedesired chemical change at the surface of this support. Supportedcatalysts, such as are supplied by the commercial catalystmanufacturers, e.g. iron, cobalt and/or nickel, alone or in combinationwith other metals such as molybdenum, tungsten, or the like are alsoamenable to such treatments to transform them to highly activecatalysts.

The then impregnated, heat-treated support is activated by treatmentwith an organometallic compound, suitably a hydrocarbon solution of anorgnometallic compound, or a hydrocarbon soluble organometalliccompound, a metallic constituent of which is selected from Groups I, IIand III of the Periodic Chart of the Elements as in Fisher ScientificCompany Copyright 1952. Preferably, the organometallic compounds includethose having the formula: QR_(n) wherein Q is equal to the metallicconstituent and is selected from Groups IA, II and IIIA having an atomicnumber of from 3 to 50, n is the valence state of Q and wherein R ishydride or an organic constituent selected from the group consisting ofsame or different, substituted or unsubstituted, saturated orunsaturated alkyl, aryl, alkylaryl, arylalkyl or cycloalkyl groupscontaining up to about 20 carbon atoms. Representative, nonlimitingexamples of the organic constituents, i.e. R include, but are notlimited to methyl, ethyl, n-propyl, isopropyl, isobutyl, secondarybutyl, tertiary butyl, n-amyl, isoamyl, heptyl, n-octyl, n-dodecyl andthe like; 2-butyl, 2-methyl-2-butyl, and the like; cyclopentylmethyl,cyclohexylethyl, cyclohexyl-propyl and the like: 2-phenylethyl,2-phenylpropyl, 2-naphthylethyl, methylnaphthylethyl and the like;cyclopentyl, cyclohexyl, 2,2,1-bicycloheptyl and the like;methylcyclopentyl, dimethylcyclopentyl, ethylcyclopentyl,methylcyclohexyl, dimethylcyclohexyl, 5-cyclopentadienyl and the like;phenylcyclopentyl, and the like, phenyl, tolyl, ethylphenyl, xylenyl,naphthyl, cyclohexylphenyl and the like. The more preferred metallicconstituent of the organic metallic compound, i.e. Q is selected fromthe group consisting of lithium, magnesium, beryllium, zinc, cadmium,mercury, boron aluminum, gallium and indium. In addition, organometalliccompounds having the formula QR_(n) X_(m) may be employed as theorganometallic compound of the instant invention where Q and R areidentical to the Q and R having been previously described, X is ahalogen, and n and m are integers ranging from 1 to 3, the summationequal to the valence of Q.

The most preferred organometallic activating agents are the tri-alkylsubstituted products of aluminum and the dialkyl halides of aluminum,particularly those containing alkyl groups having from one to about sixcarbon atoms, especially the linear alkyl groups. Exemplary of suchcompounds, which contain up to about 18 carbon atoms in the molecule,are trimethyl aluminum, triethyl aluminum, tri-n-butyl aluminum,triisobutyl aluminum, diethyl aluminum hydride, diethyl aluminumchloride, diethyl aluminum fluoride and the like. Certain volatile orhydrocarbon-soluble hydrides, for example, the various known hydrides ofboron, are also suitable activating agents as well as are the Grignardreagents.

The treatment of the supported, heat-treated catalyst with theorganometallic compound can be carried out with pure or diluted metalalkyl compounds in the liquid or vapor phase. Hydrocarbon diluents ofthe paraffinic, cyclo-parafinic or aromatic types are entirely suitable.The metal alkyl compound may be present in concentrations of 5 to 50% inthe diluent. A solution of about 20% aluminum triethyl in a paraffinicdiluent is a preferred activation system. The activation reaction isquite exothermic and it may be desirable to remove the heat ofactivation. The temperature during the activation step, which ismaintained in the range of from about 0° F. to about 500° F., preferablyfrom about 100° F. to about 200° F. Considerable gas liberation occursduring activation and these gases are normally vented from the system.The activation is allowed to proceed until reaction is no longerobserved, generally 0.5 hrs. to 2 hrs. in contact with at least someexcess of metal alkyl compound.

The treatment of the activated support material in order to obtain themost active and stable catalysts referred to above as the "fixation"step is a critical feature of the instant invention. After the supportedcatalyst has been activated with the organometallic reducing agent, itis essential that the supported catalyst be treated in the presence of agaseous stream containing hydrogen at a temperature of at least 300° F.in order to form the highly active, stable, novel heterogeneous catalystof the instant invention. Preferably, the supported activated catalystis treated in the presence of hydrogen at a temperature in the range offrom about 300° F. to about 1200° F., more preferably from about 400° F.to about 1200° F. and still more preferably between about 800° F. and1200° F. It is essential that this fixation treatment be conducted inthe presence of a gaseous stream containing hydrogen. This fixationtreatment can be carried out in the presence of inert gases such asnitrogen, helium, argon, and the like in view of the fact that hydrogenis formed "in situ" when these inert gases are employed. Necessarily,however, the fixation in the presence of such inert gases as nitrogen,helium, and argon will result in catalysts of lower activity than whenthe fixation step of the activated support catalyst is conducted totallyin the presence of a hydrogen gas.

Although nitrogen is normally considered an inert gas, there is evidencethat it may not be truly inert when present in the fixation of thesecatalyst systems. There is some evidence that gaseous nitrogen may reactwith the transition metal species at elevated temperatures. Suchreaction which may form nitrides of the metals are obviouslyundesirable. Therefore, it is preferred that the fixation step beconducted at the above critical temperatures in the presence of agaseous stream containing or resulting in the formation in the reactionzone of from about 5 to 100% hydrogen and more preferably from about 75to about 100% hydrogen. Most preferably, the fixation under theabove-described critical temperature conditions is conducted totally inthe presence of a hydrogen atomosphere. As described above, it isbelieved that the function of hydrogen during the "fixation step" whenthe supported activated catalyst is treated under the criticaltemperature limitation described above, is to fix the catalyst in astable heterogeneous form and to further reduce the transition metalcompound to a valence state to which it can more readily and completelyreact the metallic portion of the organometallic compound.

The fixation of the supported activated catalyst in the presence of ahydrogen gas under the above-described critical conditions is usuallyconducted over a period of time varying between about 1 to about 100hours, generally less time being required at higher temperatures. Asdescribed above, it is quite surprising that under optimum conditions asdescribed above, it can be shown that the activity of the catalysts ofthe instant invention increases as the length of time in which thesupported activated catalyst is being treated in the presence ofhydrogen at high temperatures, e.g. 800°-1200° F. increases. This,again, is believed to be due to the fact that the instant inventionresults in completion of a series of reactions leading to a chemicalbonding between the surface of the support and the transition metal andmetal constituent of the organometallic compound such that these metalsare not free to migrate on the surface of the catalyst and grow largecrystallites. The formation of large crystallites in conventionalsupported catalyst is generally accepted as an important mode ofcatalyst deactivation. Thus, the catalysts of the instant invention arehighly active at extremely mild hydrogenation conditions as well asexhibiting unusual stability at high severity conditions.

The fixation in the presence of hydrogen under the above-describedtemperature conditions can also be influenced by the hydrogen pressureat which such a treatment is conducted. Generally, atmospheric or nearatmospheric pressure, from about 0.5 to about 1.5 atmospheres isemployed. However, the hydrogen partial pressure may be increased in thereaction zone up to 100 atmospheres or greater. The hydrogen partialpressure will generally decrease the time-temperature requirements forforming the chemical bonding between the supports at a transition metaland metallic portion of the organometallic compounds.

The so-treated catalysts are then ready for contact with hydrogen orhydrogen-containing gases, a suitable reaction system for producinghydrogenation (or dehydrogenation) reactions. Olefins, whether singularor multiple linkage compounds, aliphatic or cyclic, and containing 2 toabout 50 carbon atoms have been readily hydrogenated to paraffins, andaromatic compounds containing from 6 to about 50 carbon atoms, and morepreferably from about 6 to about 30 carbon atoms have been saturated toproduce the corresponding cycloalkane. Acetylenic compounds, whethersingular or multiple linkage, aliphatic or cyclic in containing fromabout 2 to about 10 carbon atoms can also be hydrogenated by thecatalyst of the instant invention. In fact, catalyst formed by theimpregnation of the supports with aqueous salts of cobalt, and iron haveproven highly satisfactory despite the normally low activity attributedto cobalt and the even lower activity attributed to iron for producinghydrogenation reactions.

The catalysts can be utilized as slurries or as fixed beds, movable bedsand fluidized beds, in liquid phase or vapor phase, in batch, continuousor staged operations. Hydrogenation reactions can be carried out atremarkably low temperatures and pressures as contrasted with the moreconventional catalysts, whether the reaction is conducted in liquidphase or vapor phase. Hydrogenation reactions are generally conducted attemperatures ranging from about 0° F. to about 1000° F., and preferablyat temperatures ranging from about 100° F. to about 500° F. Thereactions can be conducted at lower than atmospheric pressures orgreater than atmospheric pressures but generally pressures ranging fromas low as about 1 atmosphere to about 500 atomspheres can be employed.Preferably, however, pressures ranging from about 1 atmosphere to about50 atmospheres are employed in conducting the reactions.

These catalysts are suitable for carrying out hydrogenation reactions insystems designed to handle high heats of reaction and severe contactingproblems, without substantial deterioration and separation of catalystfrom the support. This is due in large part to the high stability andactivity of these catalysts, by virtue of which hydrogenation reactionscan be conducted at very low hydrogen partial pressures ranging as lowas from about 1 to about 200 atmospheres.

When it is desired to carry hydrogenation reactions essentially tocompletion, an excess of hydrogen over the stoichiometric requirement isused. This excess may vary from a few percent to several hundred or evenseveral thousand percent. In the latter cases, the excess hydrogen isseparated and recycled to the system. When it is desired to carry outpartial hydrogenations, the reaction can be controlled on the basis ofhydrogen concentration, e.g. mol ratio of H₂ to feed, or reactionkinetics, e.g. using an excess of hydrogen and controlling reaction bytime, temperature, H₂ partial pressure and the like.

The activity of the catalyst is virtually unimpaired even after longperiods of use. However, there is some interference by some types ofsulfur compounds and the normal high activity of the catalyst can beimpeded very gradually. Thus, although these catalysts normally havegood resistance to sulfur-types and concentrations normally present inpetroleum oil stocks, there is evidence that certain sulfur compounds,e.g. mercaptans, tend to be adsorbed on the catalyst and may therebycause some loss of activity. In addition, impurities such as water,other oxygen-containing compounds and nitrogen-containing compounds mayalso exert a deactivating effect on the catalysts. Even this effect,however, can be curtailed or eliminated by operating the catalysts attemperatures and pressures at which adsorption of the impurities is notfavored. The conditions necessary to achieve this effect will vary withdifferent feedstocks and different impurities.

It has been unexpectedly discovered that the catalyst deactivation isreversible such that the deactivated catalyst can be restored tosubstantially its original activity, by treatment at elevatedtemperatures, preferably in the presence of a stripping gas. Examples ofsuitable stripping gases include hydrogen, nitrogen, methane and thelike. Hydrogen is preferred, and is desirably used at temperaturesranging between about 400° and 1000° F. However, broad temperatureranges which are operable in the subject process vary from about 200° to1200° F. The stripping gases should be substantially free of theimpurities that are to be removed from the catalyst, and hence arepreliminarily purified such as by drying, caustic scrubbing and drying,contacting with suitable adsorbents and the like. The amount ofstripping gas that may be used in the process varies, dependent in parton the degree of deactivation of the catalyst, the level of catalyticactivity desired to be obtained and the nature of the stripping gas. Ingeneral space velocities ranging between about 100 and 25,000 volumes ofgas per volume of catalyst per hour (V/V/Hr), preferably 500 to about1000 V/V/Hr may be used. The stripping gas may be used on a once-throughbasis or may be recycled for further use. The reactivation process isdesirably conducted in the absence of solvent. In addition, thereactivation process may be aided by conducting same in vacuo. Thereactivation is carried out for a time sufficient to achieve the desiredlevel of reactivation and generally for a time ranging between about 1and 24 hours or more. The catalysts are amenable to substantiallycomplete regeneration by (1) oxidizing with air to remove carbonaceousresidues, and (2) reactivation with aluminum alkyl compound.

These and other features of the invention will be understood byreference to the following illustrative examples.

EXAMPLE 1

These examples (1A through 1F, Table I) illustrate the criticalproperties of the catalyst supports required for this invention. Themeasurements were made by subjecting the pure, thoroughly dried anddeoxygenated supports (no transition metals present) to reaction withaluminum triethyl (in excess). Total gas liberated was metered,collected and analyzed. The total ethane produced is a direct measure ofthe hydroxyl group content of the support (J. Catalysis 7, 362 (1967)).

The supports, after treatment with excess aluminum triethyl, were heatedin nitrogen or hydrogen at 400° F., then cooled and hydrolyzed withexcess water. Gases were metered, collected and analyzed. These gasesare a quantitative measure of the functional groups associated with thealuminum triethyl fragment (theoretically -AlEt₂) now strongly bound tothe support. The tendency to form such groups as hydride particularly isa measure of the efficiency with which the supports function to give thecatalysts of this invention.

                                      TABLE I                                     __________________________________________________________________________    CHARACTERIZATION OF CATALYST SUPPORTS                                                                                    Hydride Groups                                     Hydroxyl Groups,Millimols                                                                   Fixation Conditions                                                                        after Fixation                     Example                                                                            Catalyst Support                                                                         Per Gram                                                                             Per Sq. Meter                                                                        Atmosphere                                                                           Temp.,° F.                                                                   Millimols/gm.                      __________________________________________________________________________    A    Alumina F-1                                                                              1.68   0.0060 Nitrogen                                                                             400   0.12                               B    Alumina (Alcohol-                                                             ate)       1.30   0.0064 Nitrogen                                                                             400   0.15                               C    Alumina (Alcohol-                                                             ate)       1.28   0.0063 Hydrogen                                                                             400   0.14                               D    Silica (Gr. 0-8)                                                                         0.06    0.00010                                                                             Nitrogen                                                                             400    0.004                             E    Titania Gel                                                                              0.24   0.0022 Nitrogen                                                                             400   0.19                               F    Activated Carbon                                                                         0.11    0.00008                                                                             Nitrogen                                                                             400   0.12                                    (Columbia-L)                                                             __________________________________________________________________________

It is seen from the results given in Table I that both types ofactivated alumina and titania gel are the best supports. Silica is not auseful support because of its very low hydroxyl content and virtually notendency to form hydrides. Activated carbon is not a very good supportbecause of its very low hydroxyl content although hydride groups areformed very readily at these hydroxyl sites. However, it will be shownthat the performance of activated carbon as a support for the catalystsof this invention can be enhanced by surface oxidation of the carbon.

EXAMPLE 2

One hundred grams of aqueous solution was prepared by dissolving 34grams FeCl₃.6H₂ O in 66 grams of water. One hundred grams F-1 alumina(8-14 mesh) was added to the solution and allowed to stand withoccasional mixing for about 30 minutes. A small quantity of liquid waspoured off and the catalyst freed of excess liquid by placing onabsorbent paper towels. The catalyst was dried for 3 hours in a vacuumoven at 500° F. The recovered catalyst weighed 107.4 grams, and analyzed5.3 percent iron (calculated as Fe).

A heated quartz reaction tube was charged with 25.7 grams of the abovecatalyst and a preheat area above the catalyst bed was filled withstainless steel distillation packing. The catalyst was preconditioned ina stream of dry nitrogen at a temperature of 500°-550° F. for one hourand was then cooled in nitrogen to room temperature. The reactor wasflooded from the bottom with a 20% solution of aluminum triethyl.Considerable gas was evolved and the maximum temperature reached 200° F.After 1.33 hours, the solution was withdrawn. A rapid flow of nitrogenwas introduced and the temperature was increased to 350° F. Fixation wascontinued for about 30 minutes.

The temperature in the catalyst bed was adjusted to 250° F. and a 20percent solution of benzene in cyclohexane was fed at a rate of about 11cc/hour and hydrogen gas at 60 cc/minute. The pressure in the reactionzone was essentially one atmosphere. Samples analyzed after one hour andtwo hours on conditions showed no detectable benzene by vaporchromatography, all the benzene having been hydrogenated to cyclohexane.

EXAMPLE 3

A catalyst prepared and activated in a manner essentially identical tothat described in Example 2 was used to hydrogenate a feed consisting of25 percent 1-hexyne in n-heptane at atmospheric pressure in the vaporphase. The catalyst temperature was maintained at 230°-240° F., theliquid fed at 11 cc/hour, and hydrogen gas at 60 cc/minute. The 1-hexynewas hydrogenated completely to n-hexane as shown by vapor chromatographyand confirmed by infrared spectroscopy.

EXAMPLE 4

One hundred fifty grams of F-1 activated alumina (8-14 mesh) was treatedwith 140 grams of an aqueous solution of 36% CoCl₂.6H₂ O. After dryingin vacuum for about 5 hours at 400°-450° F., 162.3 grams of intense bluecatalyst was obtained. The catalyst contained 5.3% cobalt, calculated asmetal.

Twenty-five grams of the above catalyst was charged to a quartz tube andpreconditioned at 700°-785° F. in dry nitrogen for approximately 1 hour.After cooling to room temperature in a stream of dry nitrogen, the tubewas flooded with a 20% solution of aluminum triethyl in n-heptane. Themaximum temperature in the catalyst bed reached 160° F. After about 1hour, the liquid was withdrawn and the catalyst was fixed in a flow ofdry nitrogen at 375°-400° F. for 1 hour. A 20% solution of benzene incyclohexane was fed at a rate of 11 cc/hour along with 60 cc/minute ofhydrogen. At a temperature of 216°-250° F. in the catalyst bed, thebenzene was completely hydrogenated to cyclohexane.

EXAMPLE 5

Reagent grade magnesium oxide (50 grams) was mixed with 83 grams of a40% aqueous solution of CoCl₂.6H₂ O to give a thick paste. The paste wasspread on a glass plate and dried in a vacuum oven at 250°-260° F. for 3days. The hard particles were crushed in a mortar and 10-20 meshparticles were screened out. These 10-20 mesh particles were dried for 3hours at 425°-450° F. in the vacuum oven and were light blue in colorand contained about 14 percent cobalt calculated as metal.

The quartz reaction tube was charged with 17.3 grams of the abovecatalyst which was then preconditioned in a stream of dry nitrogen at660° F. for about 30 minutes. After cooling to room temperature, thetube was flooded with 20% aluminum triethyl in n-heptane. There was verylittle heat evolved and the liquid was withdrawn after 30 minutes. Thecatalyst was fixed in dry nitrogen at 350°-365° F.

A 20% solution of benzene in cyclohexane was fed at a rate of 11 cc/hourand hydrogen at a rate of 60 cc/minute. At a catalyst temperature of240° F., hydrogenation of the benzene was better than 99% complete.

EXAMPLE 6

One hundred grams of F-1 alumina was treated with 80 grams of cobaltoctoate solution (6% cobalt dissolved in hydrocarbon vehicle) and thesolid dried in the vacuum oven. A second impregnation was carried out ina similar manner and the vacuum dried solid amounted to 113.4 grams.

Twenty-five grams of the above catalyst was charged to the quartzreaction tube, preconditioned in N₂ at 500° F. for 2 hours, thenactivated with 20% aluminum triethyl as previously described and fixedin nitrogen at 400° F. Only very slight hydrogenation of benzene wasnoted at atmospheric pressure and 240° F. Compared to Example 4, thisillustrates the advantage in catalyst activity by carrying out theoriginal impregnation in an aqueous medium with water soluble salts ofthe transition metal.

EXAMPLE 7

The catalyst described in Example 4 was used to hydrogenate o-xylene(24% in n-heptane) at atmospheric pressure and 260°-270° F.Hydrogenation was complete and two isomers of dimethyl cyclohexane wereobserved by vapor chromatography.

EXAMPLE 8

Catalysts were prepared and evaluated by the general procedure describedin Example 4 with the results shown in Table II, Examples 8A through 8E.All the cobalt catalysts contained about 5% cobalt.

                                      TABLE II                                    __________________________________________________________________________                                             Benzene                                                       Activation max. Temp.                                                                         Hydrogenation                        Example                                                                            Catalyst Base                                                                           Cobalt Salt Used                                                                        N.sub.2 Precond.                                                                      AlEt.sub.3 Treat                                                                      at 1 Atm.,250° F              __________________________________________________________________________    8A   F-1 Alumina                                                                             None      790     153     Not Active                           8B   F-1 Alumina                                                                             CoSo.sub.4 . 7H.sub.2 O                                                                 520     140     100%                                 8C   Activated Carbon                                                                        CoCl.sub.2 . 6H.sub.2 O                                                                 520     121      77%                                      (Columbia Carbon)                                                        8D   Silica Alumina                                                                          CoCl.sub.2 . 6H.sub.2 O                                                                 500     130      77%                                      Cracking Catalyst                                                        8E   F-1 Alumina                                                                             Co Acetate . 4H.sub.2 O                                                                 500     150     100%                                 __________________________________________________________________________

EXAMPLE 9

A catalyst consisting of cobalt on F-1 alumina was prepared from aqueouscobaltous acetate according to the procedure of Example 4 and contained5.3% cobalt (calculated as metal) after drying in the vacuum oven.

The quartz tube reactor was charged with 26.1 grams of the abovecatalyst which was preconditioned at 600° F. in nitrogen for 11/2 hours,then activated with aluminum triethyl and fixed in hydrogen at 400° F.

A 20% solution of n-butyraldehyde in n-heptane was hydrogenated atatmospheric pressure with the following results (expressed onsolvent-free basis).

    ______________________________________                                        Catalyst      Product Analysis, %                                             Period Temp., ° F.                                                                       n-C.sub.4 Ald.                                                                          n-C.sub.4 Alc.                                                                        Hvy. Prod.                                ______________________________________                                        1      298        0.5       91.9    7.6                                       2      300        0.5       93.2    6.3                                       3      325        1.9       89.3    8.8                                       ______________________________________                                    

EXAMPLE 10

A catalyst was prepared by impregnating 100 grams of F-1 alumina with asolution prepared by dissolving 36 grams nickel acetate.4H₂ O in 156grams water. After drying in vacuum, the catalyst was impregnated asecond time with the residual solution. After drying at 350°-400° F. invacuum, 116.3 grams catalyst was recovered which analyzed 3.4% nickel(calculated as metal).

The quartz reaction tube was charged with 25.1 grams of the nickelcatalyst which was preconditioned in nitrogen at 600° F. (1 hour), thenactivated with 20% aluminum triethyl (max. temperature 125° F.) andfixed at 400° F. with dry nitrogen.

A 20% solution of C₄ aldehydes was hydrogenated at atmospheric pressure,300°-400° F., 60 cc/minute hydrogen rate. Typical results obtainedduring an 80-hour run were:

    ______________________________________                                        Aldehyde          n-C.sub.4                                                                              n-C.sub.4                                                                              iso-C.sub.4                               ______________________________________                                        Catalyst Age, Hrs.                                                                              5        76       46                                        Aldehyde Feed, W/Hr./W                                                                          0.14     0.14     0.35                                      Temperature, ° F. Max.                                                                   308      309      400                                       Conversion, %     99.8     99.7     99.1                                      Selectivity, %                                                                 To Alcohol       95.4     97.6     96.5                                       To Heavier Products                                                                            4.6      2.4      3,5                                       ______________________________________                                    

EXAMPLE 11

Fifty grams of activated nickel catalyst prepared as described inExample 10 was charged to a 1-liter stirred autoclave along with 240 ml.n-octane and 60 cc. 2-ethyl-hexaldehyde. Five consecutive hydrogenationruns were made using the same charge of catalyst and the same volume offeed. Hydrogenation conditions and results of these five runs are shownbelow:

    ______________________________________                                                                   %                                                                             Selectivity                                        Hydrogenation Conditions   to 2-Et.                                           EX.  % Aldehyde Temp., ° F.                                                                      Press.Psig                                                                            Hrs.*                                                                              Hexanol                                ______________________________________                                        11A  20         275       500     3.5  88                                     11B  20         294       500     3.0  92                                     11C  20         340       500     1.2  97                                     11D  20         330       200     3.0  96                                     11E  50         330       500     4.5  94                                     ______________________________________                                         *Time until H.sub.2 no longer absorbed.                                  

EXAMPLE 12

A commercial cobalt molybdena on alumina catalyst containing about 3.5%CoO and 12% MoO₃ and in the form of 1/16 inch extruded rods was charged(36.7 grams) to the quartz reaction tube and was preconditioned in aflow of dry nitrogen at 600° F. for one hour. The catalyst had beencalcined at 1200° F. for 12 hours before charging to the tube. Aftercooling in dry nitrogen, the catalyst bed was flooded with 20% aluminumtriethyl. Maximum temperature reached was 160° F. After 40 minutes, thesolution was withdrawn and the catalyst fixed at 500° F. in a stream ofdry hydrogen for 15 minutes. After cooling, the catalyst was chargedwith 290 ml. n-octane and 60 ml. benzene to a 1-liter stirred autoclave.At a temperature of 225°-230° F. and a pressure of 200 psig, the benzenewas completely hydrogenated in 1 hour.

About 80 ml. of the above product was left in the reactor and a freshcharge of 160 ml. octane and 60 ml. benzene was added. This charge washydrogenated at 165°-170° F. and a pressure of 200 psig andhydrogenation was complete in about 1.5 hours. Selectivity tocyclohexane was essentially 100%.

For comparison purposes, a hydrogen reduced platinum (0.5% Pt) onalumina catalyst used for commercial scale hydrogenation of benzene wastested under conditions identical to the second hydrogenation rundescribed above. Complete hydrogenation of benzene required 2.0 hours.

EXAMPLE 13

A nickel molybdena-alumina commercial hydrotreating catalyst 10-20 meshparticle size and containing 3-4% NiO, 14-16% MoO₃ was activated withaluminum triethyl essentially as described in Example 12.

Fifty-three grams of the activated catalyst was charged to the stirredautoclave along with 240 ml. n-octane and 60 ml. benzene. Hydrogenationwas carried out at 165°-170° F. and 200 psig and the conversion of thebenzene to cyclohexane was complete in 1 hour.

EXAMPLE 14

A catalyst (57 grams), prepared from cobaltous acetate on F-1 aluminaand activated according to the procedure of Example 4, was charged tothe stirred autoclave along with 240 ml. paraffinic diluent and 60 ml.trans,trans,cis-1,5,9-cyclododecatriene. The hydrogenation conditionswere 165°-170° F. and 200 psig. Hydrogenation to cyclododecane was 96%complete in 1 hour and complete in 1.33 hours.

EXAMPLE 15

To illustrate the significant effect of type of support used, thefollowing results were obtained using cobalt catalysts (4-5% Co),prepared from cobalt acetate or cobalt chloride (Example 15C. Allcatalysts were preconditioned in dry nitrogen at 600° F., then activatedwith aluminum triethyl (20%) as described in previous examples. Finally,the catalysts were fixed in nitrogen at 400° F. Hydrogenations werecarried out with 50 ml. portions of catalyst, 240 ml. of paraffinicdiluent, and 60 ml. of benzene and the time noted for completehydrogenation of the benzene at 165°-170° F. and 200 psig.

    ______________________________________                                        Ex-                             Time to Complete                              ample          Support          Hydrogenation,Hrs                             ______________________________________                                        15A   F-1 Alumina (Alcoa)   2.03                                              15B   F-10 Alumina (Alcoa)  1.25                                              15C   H-151 Alumina (Alcoa) 3.22                                              15D   471A Alumina          5.0                                               15E   Alcoholate Alumina    1.25                                              15F   "Celite" (Johns-Manville)                                                                           10.0                                              15G   Activated Carbon (Pittsburgh Coke)                                                                  4.75                                              ______________________________________                                    

The F-10 alumina and the alcoholate alumina were the purest aluminabases used and these gave the highest catalytic activity. Aluminascontaining 2-6% silica (H-151 and 471A) gave less active catalysts. The"Celite" is largely silica and is not a useful catalyst support. The loworder of activity is probably due to formation of some cobalt metalrather than to the catalyst complexes of this invention.

EXAMPLE 16

Catalysts containing 5-6% Fe on F-1 alumina were prepared from ferricchloride.6H₂ O, ferrous chloride.4H₂ O and ferric nitrate.9H₂ O anddried in the vacuum oven. The catalysts were preconditioned at 800° F.in dry nitrogen and then contacted with aluminum triethyl at roomtemperature (maximum temperature during activation was about 200° F.).The catalysts were treated in nitrogen at 400° F. for fixation. Sampleswere taken after the 800° F. N₂ preconditioning and after the final 400°F. N₂ fixation for examination by Mossbauer spectrometry to determinethe valence state of the iron, and for correlation with catalyticactivity. The results obtained were as follows:

    __________________________________________________________________________                   Mossbauer Results, %                                                                          Time, Hrs.,                                                   preconditioned                                                                        Fixed    for Benzene                                   Salt Used In   Catalyst                                                                              Catalyst Hydrogenation                                 Example                                                                            Preparation                                                                             Fe.sup.+3                                                                         Fe.sup.+2                                                                         Fe.sup.+3                                                                         Fe.sup.+2                                                                         165  F. 200 psig                               __________________________________________________________________________    16A  FeCl.sub.3 . 6H.sub.2 O                                                                 100 0   15  85  1.3                                            16B  FeCl.sub.2 . 4H.sub.2 O                                                                 100 0   10  90  1.4                                            16C  Fe(NO.sub.3).sub.3 . 9H.sub.2 O                                                         100 0   60  40  (1)                                            __________________________________________________________________________

(1) Catalyst not active at 165° F., 200 psig, but benzene hydrogenationwas complete in 1.8 hours at 300° F., 400 psig. The catalysts preparedfrom chloride had high activity and high concentrations of Fe⁺² in thefinal activated (fixed) state while the catalyst prepared from nitratehad a much lower order of activity and a much lower concentration ofFe⁺². No metallic iron was detectable.

EXAMPLE 17

Zinc oxide (442 grams) was mixed with a solution of 93.5 grams nickelacetate.4H₂ O in 450 ml. warm water to give a thick paste. The mixturewas dried in the vacuum oven giving chunks of greenish-white solid. Thesolid was broken in a mortar and screened to 10-20 mesh size.

The 10-20 mesh catalyst was charged to a heated quartz tube,preconditioned at 600° F. for one hour in a nitrogen atmosphere, thenactivated with aluminum triethyl and then fixed in nitrogen at 400° F.

The above catalyst (55 grams) was mixed with 250 ml. iso-octane and 50ml. benzene in a one-liter autoclave and the hydrogenation of thebenzene was complete in 5.2 hours at 165° F. and 200 psig.

EXAMPLE 18

These examples show that magnetic susceptibility measurements on typicalcatalysts of this invention confirm that the Group VIII nonnoble metalsare present in the +2 valence state. All catalysts were prepared on F-1alumina base and, containing 4-6% equivalent metal, were activated inthe liquid phase with triethyl aluminum (20% solution), then fixed in anitrogen atmosphere at 400° F. The iron catalysts derived from FeCl₃ andFe(NO₃)₃ were the same catalysts in which the Mossbauer measurementsdescribed in Example 16 were made.

    ______________________________________                                        Salt Used to                                                                             Magnetic Moment, μ after                                                                    Literature Values                                 Impregnate Base                                                                          Activation and Fixation                                                                        Fe.sup.+2                                                                             Fe.sup.+3                                 ______________________________________                                        FeSO.sub.4 5.18             5.1     5.9                                       FeCl.sub.3 5.35                                                               Fe(NO.sub.3).sub.3                                                                       5.29                                                                                           Ni.sup.+2                                         NiSO.sub.4 2.92             3.1                                                                           Co.sup.+2                                         CoSO.sub.4 4.79             5.2                                               ______________________________________                                    

Literature values are for these elements in octahedral configuration.For the iron catalysts, the values are in good agreement forpredominantly an Fe⁺² configuration but containing a small amount ofFe⁺³ contaminant (as shown by the Mossbauer data in Example 16). Only inthe case of the catalyst derived from Fe(NO₃)₃ was a minute trace (about85 ppm) of metallic iron detected.

The nickel and cobalt catalysts (Ni⁺² and Co₊₂ salts used inpreparation) are in fairly good arrangement but slightly lower inmagnetic moment than the literature values. It is well known thatdistorted configurations such as would exist on a support surface willlower the magnetic moment.

EXAMPLE 19

A catalyst containing 6.5 weight % iron was prepared by impregnating analcoholate type alumina with aqueous iron nitrate. In the followingtable the benzene hydrogenation activity of this catalyst, activated inaccordance with this invention (preconditioned at 800° F. in N₂ andfixed as indicated), is compared with the activity of the same catalystactivated by severe hydrogen treating.

    __________________________________________________________________________    Example        19A           19B  19C                                         __________________________________________________________________________    Catalyst       6.5% Fe on PF Alumina                                           AlEt.sub.3 Treat                                                                            None          Standard Treat                                   Fixation (H.sub.2 Atm.)                                                        Temp., ° F.                                                                          1200          400  1200                                         Time, Hrs.     16            1    16                                         Mossbauer Summary    Before  After                                                                              After                                       Estimated % of Fe as AlEt.sub.3 Treat                                                                      Fixation                                                                           Fixation                                     Fe.sup.+3     --    85      65   50                                           Fe.sup.+2     --    --      25   20                                           Alpha Fe.sub.2 O.sub.3                                                                      --    15      --   --                                           Alpha Fe      --    --      10   30                                          Time, Hrs., to Compl.                                                                        1000+         3.2  3.3                                         Abs. Hydro. Act.mol/hr/gm                                                      Fe            <0.0001       0.34  0.37                                       __________________________________________________________________________

The catalyst activated by hydrogen alone is essentially inactive forbenzene hydrogenation (at 212° F., 600 psig). There are only slightdifferences in activity between the mildly fixed (400° F.) and severelyfixed (1200° F.) catalysts. The Mossbauer results (presence of alphairon) indicate that this catalyst contained too high an ironconcentration for maximum activity and complete stabilization.

EXAMPLE 20

A catalyst similar to that of Example 19 was prepared from iron nitrateon the same alumina base, except that the iron content was 3.2 wt. %.This catalyst was activated according to the procedure used for Example19B, activity for benzene hydrogenation was 0.04 mol/hr./gm. Fe at 212°F. and 0.38 mol/hr./gm. Fe at 300° F. The same charge of catalyst wasplaced back in the tube and heated in hydrogen for 16 hours at 1200° F.The hydrogenation activity tests were repeated. At 212° F. the activitywas 0.54 mol/hr./gm. Fe and at 300° F. was 2.4 mol/hr./gm. Fe. At thismore optimum iron concentration and more optimum Al/Fe ratio, thisstabilization of the iron by the aluminum is much more complete and theactivity is enhanced on the order of tenfold or more.

EXAMPLE 21

A series of iron catalysts containing 0.8, 1.6, 3.2 and 6.4 percent Fewere prepared on the alcoholate type alumina base. The base contains 1.2millimols/gm. --OH group equivalent and the Fe was impregnated on thebase as FeCl₃.6H₂ O. The catalysts were activated by preconditioning at600° F. (N₂ atmosphere), treating with 20 percent AlEt₃ in n-heptane,then fixed in hydrogen at 400° F. Activities were determined on anabsolute basis (mols.benzene hydrogenated per hour per gram Fe) in astandard hydrogenation test at 212° F. and 600 psi H₂ pressure. Resultsof these tests were:

    ______________________________________                                                           Hydrogenation Rate,                                                  Mole Ratio                                                                             mol/hr./gm. Fe                                             Run   Wt. % Fe  Fe/OH      212° F.                                                                         300° F.                            ______________________________________                                        A     6.4       1.01       1.94     --                                        B     3.2       0.49       2.60     --                                        C     1.6       0.24       1.11     --                                        D     0.8       0.12       0.17     1.18                                      ______________________________________                                    

The results are very striking in showing the critical effect oftransistion metal/hydroxyl group ratio in preparing these catalysts.There is a fairly sharp maximum in catalytic activity occuring at anFe/OH molar ratio at about 0.5. However, even at the greatly nonoptimumratio of 0.12, the activity of catalyst is increased more than six-foldby increasing the temperature to 300° F.

EXAMPLE 22

This example is to show the positive identification of Fe--Al linkagesin high activity iron catalysts prepared according to this invention.Also, it is designed to show the amount of iron present in the activecatalytic state. The method is based on hydrolysis of the activated,fixed catalysts with deuterium oxide, and that (1) hydride groups on Alor Fe will give HD on deuterolysis, and (2) --Al--Fe direct linkageswill give D₂ on deuterolysis. Thus the D₂ make will be a direct measureof --Al--Fe groups.

The two most active catalysts from Example 21 (6.4% Fe and 3.2% Fepreconditioned at 600° F.) were used in these tests. All gases liberatedduring the treat with 20% AlEt₃, during the hydrogen fixation and duringthe deuterolysis with excess D₂ O were metered, collected and analyzed.The deuterolysis gases were analyzed for HD, D₂ and deuteratedcomponents of methane and ethane in addition to the usual components.Results of these exhaustive tests for the two iron catalysts were:

    ______________________________________                                        Example              22A       22B                                            ______________________________________                                        Catalyst, Wt. % Fe   6.4       3.2                                            Total Deuteralysis Gas, mmol./gm.                                             Cat                  1.52      1.78                                           D.sub.2 Made, mmol./gm. Cat.                                                                       0.41      0.34                                           HD Made, mmol./gm. Cat.                                                                            0.34      0.39                                           D.sub.2, Mole % on Fe                                                                              36        59                                             Hydrogenation Activity, mol./hr./                                             gm. Fe               1.94      2.60                                           ______________________________________                                    

The D₂ concentration expressed as mol % on Fe represents the percent ofiron as the catalytically active species, that is, having an average ofone iron to aluminum direct chemical bonds. The catalyst bonding thegreater percent iron in this form is the same as the catalyst of Example21 Run B.

EXAMPLE 23

To illustrate the criticality of preconditioning the catalyst atelevated temperatures, the catalyst containing 6.4% Fe (as FeCl₃) on thePF (alcoholate) alumina base was activated as described in Example 21except that the temperature of preconditioning was varied from 300° F.to 600° F. to 900° F. in nitrogen atmosphere for 2-hour periods.Activity was measured by the benzene hydrogenation test.

    ______________________________________                                                Preconditioning                                                                             Absolute Hydrogenation                                  Example Temp., ° F.                                                                          Rate, Mol./Hr./Gm. Fe                                   ______________________________________                                        23A     300           0.26                                                    23B     600           1.94                                                    23C     900           1.60                                                    ______________________________________                                    

These results show clearly that an inferior catalyst results at lowpretreat temperatures. At the highest temperature, 900° F., somecrystallite growth may have occurred since the high stabilitycharacteristic of these catalysts is not realized prior to the alkyltreat and fixation in the presence of hydrogen.

EXAMPLE 24

A catalyst containing 6.5% Fe was prepared by impregnating silica gel(Davison Grade 0-8) with FeCl₃ aqueous solution. The catalyst waspreconditioned at 800° F., treated with 20% AlEt₃ solution, then fixedin hydrogen at 400° F. Activity for benzene hydrogenation was notmeasurable at 212° F. and was on the order of 0.002 mol./hr./gm. Fe at300° F. This silica-based catalyst is essentially inactive because anyhydroxyl groups in the silica base undergo alkylation to give --Si--Etgroups rather than the necessary --Si--O--AlEt₂ groups.

EXAMPLE 25

This example is designed to show the importance of hydroxylfunctionality on a support such as activated carbon. Colombia activatedcarbon Grade L (surface area 1350 sq.in./gm.) was impregnated with anaqueous solution of ferric chloride to give 6.0 wt. % Fe. Another sampleof the carbon was air-oxidized at 500° F. for 16 hours and thenimpregnated to give 6% Fe. Both catalysts were preconditioned for 2 hrs.at 600° F. in N₂ atmosphere, treated with triethyl aluminum (20%solution), then fixed in hydrogen for 1 hour at 400° F. Benzenehydrogenation activities were as follows for these catalysts.

    ______________________________________                                                     Hydrogenation Activity                                           Benzene      mol./hr./gm. Fe                                                  Hydrogenation                                                                              Carbon Base Not                                                                              Carbon Base                                       Temperature, ° F.                                                                   Preoxidized    Preoxidized                                       ______________________________________                                        212          0.023          0.040                                             300          0.053          0.130                                             392          0.155          0.360                                             ______________________________________                                    

Preoxidation of the carbon base more than doubles the activity of thecatalysts. However, compared to activated alumina, carbon is arelatively poor base for these catalysts because its hydroxylfunctionality is far from optimum, even after oxidation.

EXAMPLE 26

A titania gel base having a surface area of 106 sq. meters/gm. wasdetermined to have a hydroxyl group content of 0.24 millimols/gm. asdescribed in Example 1. This base (100 grams) was impregnated with asolution prepared by dissolving 17 gms. FeCl₃.6H₂ O in sufficient waterto give 65 cc. of solution. Essentially all the solution was absorbedand the iron content of the catalyst was 3.2 wt. % after drying in thevacuum oven.

A 50 cc. portion of the catalyst was activated as follows: (a)preconditioned at 600° F. for 2 hours in a flow of dry nitrogen; (b)treated with an excess of 20% AlEt₃ solution--maximum temperature was192° F.; and (3) fixation in hydrogen for one hour at 400° F.

The activated catalyst (56.4 gms.) was charged with 250 cc. of benzeneto the stirred autoclave and a hydrogenation test carried out at 212° F.and 600 psig H₂ pressure. The hydrogenation was complete in 11/2 hoursand the catalytic activity calculated to be 1.03 mol./hr./gm. Fe.

EXAMPLE 27

The iron catalyst containing 3.2% Fe derived from iron nitrate on thealcoholate alumina base was activated with diethyl zinc and triethylboron in comparison with triethyl aluminum. The catalyst preconditioningactivation and fixation conditions and hydrogenation activities were asshown in the table below:

    ______________________________________                                        Example           27A      27B      27C                                       ______________________________________                                        Alkyl Used        AlEt.sub.3                                                                             BEt.sub.3                                                                              ZnEt.sub.2                                Preconditioning Temp., ° F.                                                              600      600      600                                       Alkyl Treat, temp., ° F. (Max)                                                           200      500      190                                       Fixation (H.sub.2 Atm.)                                                        Temp., ° F.                                                                             400      400      1200                                       Time, Hrs.       1        1        16                                        Hydrogenation Activity,                                                       mol./hr./gm. Fe   0.38     0.031    0.11                                      At Temp., ° F.                                                                           300      392      392                                       ______________________________________                                    

EXAMPLE 28

A catalyst having a very low nickel concentration (0.6 Wt. % Ni) wasprepared by impregnating the alcoholate alumina base with an aqueoussolution of nickelous acetate. Hydrogenation activities for activationwith hydrogen alone and by the method of this invention are compared inthe table.

    ______________________________________                                        Example            28A      28B     28C                                       ______________________________________                                        Catalyst           0.6% Ni on PF Alumina                                      AlEt.sub.3 Treat   None     Standard                                          Fixation (H.sub.2 Atm.)                                                        Temp., ° F.                                                                              1200     400     1200                                       Time, Hrs.        16       1       16                                        Time, Hrs. to Completion                                                                         45       5.3     3.2                                       Abs. Hydro. Act., mol/hr/gm Ni                                                                   0.31     2.2     3.7                                       ______________________________________                                    

EXAMPLE 29

The noble metals of Groups VIII are also converted to highly active andstable catalyst by the technique of this invention. However, the noblemetals, because of cost and activity considerations, are generally usedin very low concentrations, e.g., 0.1-1.0%, on the support. With theusual supports, this results in very high alkyl metal-to-noble metalmolar ratios (e.g., 20/1 to 100/1). Under such conditions and at mildfixation severity, the noble metal may be overwhelmed or buried by thealkyl metal resulting in low catalyst activity. But it has been foundthat at very severe fixation conditions this effect is overcome andhighly active and extremely stable catalysts result.

A 0.6% platinum on alcoholate alumina was prepared by impregnation withaqueous chloroplatinic acid. The activity of this catalyst at severalseverities of hydrogen activation was as follows:

    ______________________________________                                        Example       29A       29B        29C                                        ______________________________________                                        Catalyst      0.6% Pt on Alcoholate Alumina                                   H.sub.2 Reduction Cond.                                                        Temp., ° F.                                                                         800       1200       1200                                        Time, Hrs.   2.5       2.5        18.5                                       Time, Hrs. to Compl.                                                                        0.90      1.33       1.75                                       ABS Hydro. Act.*                                                                            22.8      18.0       12.2                                       ______________________________________                                         *Mol./hr./gm. Pt.                                                        

The decreasing activity with increasing severity of hydrogen reductionis attributed to growth of larger crystallites of platinum metal. Itwas, however, not possible to detect this by X-ray at this low platinumconcentration.

    ______________________________________                                        Example         29D     29E     29F   29G                                     ______________________________________                                        Catalyst        0.6% Pt on Alcoholate Alumina                                 AlEt.sub.3 Treat                                                                              Standard                                                      Fixation (H.sub.2 Atm.)                                                        Temp., ° F.                                                                            400    800     1200  1200                                     Time, Hrs.     1       2.5     16    32                                      Time, Hrs. to Compl.                                                                          53      15.8    1.6   0.67                                    ABS Hydro. Act. mol/hr./                                                       gm. Pt         0.37    1.40    11.8  17.2                                    ______________________________________                                    

Here it is noted that the activity of the catalyst is increasing withincreasing hydrogen fixation severity and that the low activitycharacteristic of mild fixation (Example 29D) is completely overcome.The extreme stability of the catalyst of Example 29G is typical of noblemetal catalysts activated by the methods of this invention. Anequivalent time-temperature exposure in hydrogen activation (orreactions with hydrogen) would give a predicted activity in the range of5- mol/hr./gm. Pt.

EXAMPLE 30

A molybdenum catalyst containing 13 wt. % MoO₃ was prepared byimpregnating 200 grams of the alcoholate alumina base with a solution of38 grams ammonium molybdate (82% MoO₃) dissolved in 120 cc. water. Allliquid was absorbed and the catalyst was dried in the vacuum oven.

A 50 cc. portion of this catalyst was charged to the quartz tube andheated in a flow of dry nitrogen at 800° F. for 2 hours. After coolingto room temperature, the catalyst was treated with 20% triethyl aluminumgiving a transient maximum temperature of 195° F. After one hour, theliquid was withdrawn and the catalyst was fixed in hydrogen at 400° F.for 11/2 hours.

Thirty-nine grams of the activated catalyst and 250 cc. of benzene werecharged to a stirred autoclave and a hydrogenation was carried out at212° F. and 600 psig H₂ pressure. The reaction was complete in 3 hoursand the calculated rate of hydrogenation was 0.28 mol benzenehydrogenated per hour per gram of molybdenum.

EXAMPLE 31

In the data tabulated below, the 13% MoO₃ on alcoholate alumina catalystis used to show the effects of

(1) Hydrogen activation vs. the activation method of this invention. (2)Increasing severity of fixation in a hydrogen atmosphere. (3) Fixationin hydrogen compared to fixation in nitrogen at high severity. (4) Theactivation method of this invention in inhibiting formation of largecrystallites of transition metals (free metals).

    __________________________________________________________________________    Example     31A  31B  31C  31D 31E  31F                                       __________________________________________________________________________    Cat. Activation                                                               AlEt.sub.3 Treat                                                                          None      Standard Treat(a)                                       Fixation                                                                      Atmosphere  Hydrogen                Nitrogen                                  Temp.,° F.                                                                         1200 1200 400  900 1200 800                                       Time, Hrs.  16   44   1    16  16   16                                        Hrs. to Completion                                                                        69   91   3.3  1.83                                                                              1.60 6.6                                       Abs. Hydro. Act.(b)                                                                       0.012                                                                              0.0096                                                                             0.27 0.42                                                                              0.53 0.12                                      Rel. Mo Metal(c)                                                                          0.69 1.00 0.000                                                                              --  0.036                                                                              0.012                                     __________________________________________________________________________     (a)Catalyst heated at 800° F. in N.sub.2 flow for 2 hours, cooled,     treated with an excess of 20% AlEt.sub.3 at room temperature.                 (b)Mols benzene hydrogenated per hour per gram of metal.                      (c)By x-ray diffraction, relative values based on most severely reduced       catalyst = 1.00.                                                         

Examples 31C, D and E show the effects of increasing severity offixation in the presence of hydrogen.

Examples 31C, D, and E, in comparison with Examples 31A and B, show theactivation method of this invention in comparison with hydrogenactivation. The x-ray diffraction data for these runs show how thetechnique of this invention stabilizes the active catalytic species in avery stable, highly dispersed form.

Examples 31D and F show the effects of fixation in nitrogen compared tofixation in hydrogen and that the presence of hydrogen during fixationresults in a significant increase in the hydrogenation activity of thecatalyst.

EXAMPLE 32

A catalyst containing about 10 wt. % tungsten was prepared byimpregnating 200 gms. of alcoholate type alumina with an aqueoussolution prepared by dissolving 31 grams of ammonium meta tungstate in110 cc. water. All solution was taken up.

A 50 cc. portion of the above catalyst was changed to an electricallyheated quartz tube and heated at 850° F. in a flow of dry nitrogen for 3hours.

After cooling to room temperature, the catalyst bed was flooded from thebottom with a 20% solution of triethyl aluminum in n-heptane. Thetemperature rose transiently to 190° F. and much gas was evolved. After30 minutes the solution was drained off and the catalyst was then heatedin nitrogen at 400°-420° F. for one hour.

Forty grams of the above catalyst and 250 cc. benzene were charged to astirred autoclave and a hydrogenation was carried out at 212° F. and 600psig H₂ pressure. Gas was absorbed at a rate of 20 lbs. per minute andthe reaction was complete in 4.1 hours. The absolute rate ofhydrogenation was calculated to be 0.17 mole of benzene hydrogenated perhour per gram of tungsten.

Another run made with the same catalyst at 260° F. gave a hydrogenationrate of 0.31 mol/hr./gm. of tungsten.

EXAMPLE 33

The results tabulated below were obtained with two tungsten catalysts onalcoholate type alumina having respective tungsten concentrations of 27percent WO₃ and 9 percent WO₃. These results will show the effects ofthe concentration of the transition metal, in this case, tungsten.

    __________________________________________________________________________    Example     33A  33B  33C   33D  33E  33F                                     __________________________________________________________________________    WO.sub.3 conc.,                                                               wt. %       27   27   27    9    9    9                                       Activation                                                                    AlEt.sub.3 Treat                                                                          None Standard   None Standard                                     Fixation (H.sub.2)                                                            Temp.,° F.                                                                         1200 400  1200  1200 400  1200                                    Time, Hrs.  16   1    16    16   1    16                                      Hrs. to Compl.                                                                            153  3.6  77    1000 5.6  5.7                                     Abs. Hydro. Act.,                                                             Mol/hr./gm. W                                                                             0.0017                                                                             0.057                                                                              0.0028                                                                              0.0001                                                                             0.18 0.18                                    X-Ray Eval. Most W                                                                             No   W metal,                                                                            No W No W No                                                  metal                                                                              cryst.                                                                             possi-                                                                              metal                                                                              metal                                                                              cryst.                                              also forms                                                                              bly WO.sub.2                                                                        possi-                                                                             less form                                                WO.sub.2 &                                                                         of W & W.sub.3 O.                                                                        ble  WO.sub.2                                                                           of W                                                W.sub.3 O                                                                          metal      small                                                                              than metal                                               W>WO.sub.2                                                                         or         conc.                                                                              Ex.33D                                                                             or                                                  ≅W.sub.3 O                                                               oxides.    WO.sub.2  oxides.                                 __________________________________________________________________________

Examples 33A, B and C with the high tungsten concentration show that theAlEt₃ activated, hydrogen fixed catalyst (Example 33B) is more than 50times as active as the catalyst activated by hydrogen (Example 33A).However, this catalyst is unstable at higher severity hydrogen fixation.The Al/W ratio (Al from AlEt₃) is insufficient to stabilize this amountof tungsten.

The Al/W ratio is much more favorable at the 9% WO₃ concentration andmost of the tungsten is stabilized, does not undergo crystallite growth,and activity remains constant as fixation severity is increased (compareExample 33F with Example 33E).

EXAMPLE 34

Results obtained at a still lower tungsten concentration (6% WO₃ on thealcoholate alumina base) show a striking enhancement in activity asfixation severity is increased.

This catalyst, when given the standard AlEt₃ activation (as in Example33) and fixed in hydrogen for 1 hour at 400° F., had a benzenehydrogenation activity of 0.10 mol/hr./gm. W. The same catalyst was thenplaced back in the activation tube and given an additional fixation of16 hours at 1200° F. in hydrogen. This catalyst then showed an activityof 0.71 mol/hr./gm. W. This high activity is now completely stabilized.

EXAMPLE 35

A catalyst was prepared by impregnating 200 gms. of F-1 alumina with asolution of 3 ml. perrhenic acid (1.3 gms. Re/ml.) made up to 120 ml.with water. All solution was absorbed. Catalyst was dried in the vacuumoven and had a rhenium content of 2.0 wt. %.

The quartz activation tube was charged with 55 cc. of the above catalystand heated in a flow of dry nitrogen at 600° F. for 2 hours. Aftercooling to room temperature, the catalyst bed was flooded from thebottom with a 20% solution of aluminum triethyl. The maximum temperaturereached 210° F. After one hour, the solution was drained off and thecatalyst was fixed in hydrogen for one hour at 400° F.

The stirred autoclave was charged with 51.5 gms. of the above catalystand 250 cc. of a 20% solution of benzene in n-octane.

At a temperature of 260° F. and a hydrogen pressure of 500 psig, thebenzene was hydrogenated at a rate of 0.22 mol/hr./gm. Re.

EXAMPLE 36

A catalyst was prepared by impregnating 200 gms. F-1 alumina with asolution prepared by dissolving 40 gms. CrO₃ in sufficient water to givea total volume of 125 ml. All liquid was absorbed. The catalyst wasdried in the vacuum oven and the chromium content was 9 wt. %.

The catalyst (60 cc.) was activated as follows: (1) heated in air for 16hours at 1000° F.; (2) heated in dry nitrogen for 1 hour at 1000° F.;(3) cooled to room temperature and treated with an excess of aluminumtriethyl (20% solution), maximum temperature reaching 240° F.; and (4)finally treating in hydrogen for 2 hours at 400° F.

The activated catalyst (49 gms.) was charged to the stirred autoclavewith 250 cc. benzene. Hydrogenation at 300° F. and 600 psig H₂ pressuregave a measured reaction rate of 0.062 mol of benzene hydrogenated perhour per gram of chromium.

EXAMPLE 37

A catalyst was prepared by impregnating 200 gms. of alcoholate typealumina with a solution of 38 gms. ammonium vanadate dissolved in amixture of 80 cc. of water and 60 cc. of monoethanolamine, the latteradded to aid in dissolving the ammonium vanadate. After drying in thevacuum oven, the catalyst contained 7.5% vanadium.

The catalyst was activated as follows: (1) heated in air for 71/2 hoursat 1000° F.; (2) heated in dry nitrogen for 1 hour at 800° F.; (3)cooled to room temperature and treated with an excess of aluminumtriethyl (20% solution), maximum temperature reaching 205° F.; and (4)fixation in hydrogen at 400° F. for 1 hour.

The activated catalyst (41 gms.) was charged to the autoclave with 250cc. of benzene. Hydrogenation at 212° F. and 600 psig H₂ pressure gave ahydrogenation rate of 0.08 mol/hr./gm. vanadium and at 300° F. and 600psig the rate increased to 0.21 mol/hr./gm.

EXAMPLE 38

A catalyst containing 6 wt. % copper was prepared by impregnating 200gms. F-1 alumina with a solution prepared by dissolving 34 gms. CuCl₂--2H₂ O in sufficient water to give 160 cc. solution. All solution wasabsorbed and the catalyst was dried in the vacuum oven.

The activation tube was charged with 47.2 gms. of the catalyst, theweight being determined after preconditioning the catalyst at 800° F.for 2 hours in dry nitrogen. The catalyst was then activated with anexcess of aluminum triethyl and fixed in hydrogen at 400° F. for onehour.

The fixed catalyst was then hydrolyzed with deuterium oxide and gasesevolved were collected and analyzed. The gases were principally C₂ H₅ D,D₂ and HD, the latter two components amounting to 0.18 and 0.07millimols per gram of catalyst, respectively. This amount of D₂corresponds to 19 percent of the copper bonded directly to aluminum andan average of 4 mol % hydride (based on copper) associated with thecopper-aluminum complex.

This catalyst had relatively low activity for hydrogenation of benzene,the activity being determined as 0.033 mol/hr./gm. Cu at 392° F. and 600psig H₂ pressure.

EXAMPLE 39

A catalyst containing 6 wt. % manganese was prepared by impregnating 200gms. of alcoholate alumina with a solution prepared by dissolving 54gms. manganous acetate (4 H₂ O) in sufficient water to give 225 cc. ofsolution. Essentially all liquid was absorbed and the catalyst was driedin the vacuum oven.

A 50 cc. portion of the catalyst was placed in the heated quartz tubeand preconditioned at 800° F. in a flow of dry nitrogen for 2 hours. Thetemperature was then reduced to 400° F. and aluminum triethyl (20%)solution was added dropwise over a period of 1 hour. The temperaturemaximum was 565° F. After one hour the alkyl solution was cut off andthe catalyst was fixed at 400° F. in a stream of dry hydrogen.

Thirty-six grams of the activated catalyst was charged to the stirredautoclave with 250 cc. benzene. At 392° F. and 600 psig H₂ pressure, thehydrogenation rate was 0.015 mol/hr./gm. Mn.

EXAMPLE 40

A catalyst containing about 7 wt. % nickel was prepared by threeconsecutive impregnations of 500 gms. F-1 alumina with solutionscontaining 50 gms. nickel acetate (0.4H₂ O) in sufficient water to give250 cc. solution. The catalyst was dried in the vacuum oven betweenimpregnations.

The activation tube was charged with 50 cc. of this catalyst which waspreconditioned by heating at 800° F. for 2 hours in a flow of drynitrogen. After cooling to room temperature, the catalyst was treatedwith an excess of a 20% solution of diethyl aluminum fluoride inn-heptane. After standing for about 1 hour, the solution was drawn offand the catalyst was fixed in a flow of dry nitrogen at 400° F. for 1hour. The catalyst was analyzed and contained 6.4% nickel and 2.5%fluorine.

The stirred autoclave was charged with 43.4 gms. of the above activatedcatalyst and 250 cc. of benzene and a hydrogenation reaction was carriedout at 212° F. and 600 psig H₂ pressure. The hydrogenation rate of thebenzene was 0.39 mol/hr./gm. Ni.

EXAMPLE 41

The following example demonstrates the effectiveness of the reactivationprocess of the subject invention. A catalyst containing about 10 wt. %tungsten, based on total weight of catalyst, on alcoholate alumina wasprepared by impregnating the alumina base with an aqueous solution ofammonium meta tungstate and drying in a vacuum oven. The catalyst wasactivated as follows:

Fifty (50) cc of the catalyst was charged to a quartz tube and heated ina stream of dry nitrogen for two hours and cooled under nitrogen. Thetube and catalyst bed were then flooded from the bottom with a 20%solution of triethyl aluminum in n-heptane. A vigorous reaction occurredwith considerable gas liberation and the temperature rose from roomtemperature to about 190° F. After the reaction subsided the solutionwas withdrawn. The catalyst was subsequently fixed by heating in a flowof dry hydrogen at 400° F. for one hour and then cooled under drynitrogen.

The catalyst as prepared above was charged to a 1-liter stirredautoclave with 250 cc of benzene and a hydrogenation reaction conductedat 212° F. and 500-600 pounds by hydrogen pressure. The hydrogenation ofthe benzene followed zero order kinetics. After the reaction wassubstantially complete, the liquid product was withdrawn from theautoclave and a fresh charge of 250 cc of benzene introduced therein.Additional cyclic batch hydrogenation runs were carried out in the samemanner. Catalyst deactivation was determined by the change in rateconstant with cycles of operation at 212° F. Typical results are shownbelow:

    ______________________________________                                                         ZERO ORDER                                                   HYDROGENATION    RATE CONSTANT                                                CYCLE NUMBER     %/HR.                                                        ______________________________________                                        1                23.7                                                         3                13.0                                                         4                 8.8                                                         ______________________________________                                    

After the fourth cycle, the catalyst was placed back in the quartz tubeand treated at 600° F. for 1 hour in a flow of dry hydrogen. Theregenerated catalyst was charged to the autoclave with a fresh 250 cccharge of benzene. A hydrogenation rate constant of 22.7 was determinedat 212° F. and 500-600 psi hydrogen pressure, indicating that thecatalyst had been regenerated to very near its initial activity.

What is claimed is:
 1. A process for the hydrogenation of a feedcontaining C₄ -C₈ aldehydes comprising the steps of:forming a catalystby impregnating a support containing at least about 0.1 millimoles ofhydroxyl groups per gram of support, said support comprising aluminawith an aqueous solution of a transition metal salt comprising nickelacetate; heat-treating the impregnated support at a temperature of atleast about 500° F.; activating the heat-treated impregnated support bycontacting same with an organometallic compound having the formula:QR_(n), wherein Q is selected from Group I, II or III metals of thePeriodic Chart of the Elements, R is selected from the group consistingof hydride and alkyl, aryl, alkaryl, aralkyl and cycloalkyl radicalscontaining from 1 to about 20 carbon atoms and wherein n ranges from 1to 3 and satisfies the valence of Q; treating the activated supportedmetal complex in the presence of hydrogen at a temperature of at leastabout 300° F; and thereafter contacting said catalyst with said feed inthe presence of a hydrogen-containing gas, thereby producing ahydrogenation reaction.
 2. The process of claim 1 wherein thehydrogenation reaction is conducted at a temperature in the range offrom about 0° to about 1000° F. and at a pressure ranging between about1 and 50 atmospheres.
 3. The process of claim 1 wherein said catalyst isat least partially deactivated as a result of contacting same with saidfeed in the hydrogenation reaction, and where said deactivated catalystis at least partially reactivated by treatment of same at elevatedtemperature in the presence of a stripping gas.
 4. The process of claim3 wherein said stripping gas is selected from the group consisting ofhydrogen, nitrogen and methane.
 5. The process of claim 4 wherein saidstripping gas is hydrogen.
 6. The process of claim 3 wherein saidelevated temperatures range between about 200° to 1200° F.
 7. Theprocess of claim 3 wherein the space velocity of the stripping gasranges from about 100 to about 25,000 volumes of gas per volume ofcatalyst per hour.
 8. The process of claim 1 wherein said catalyst is atleast partially deactivated as a result of contacting same with saidfeed in the hydrogenation reaction, and where said deactivated catalystis at least partially regenerated by (1) oxidizing same with air and (2)reactivating by contacting said oxidized catalyst with a trialkylaluminum compound wherein the alkyl group contains from 1 to about 6carbon atoms.
 9. The process of claim 1 wherein Q has an atomic numberof from 3 to 50, and wherein QR_(n) is a trialkyl aluminum compound. 10.The process of claim 1 wherein the activated supported metal complex istreated in the presence of hydrogen at a temperature above about 800° F.11. The process of claim 1 wherein the amount of transition metalimpregnated on the support is in the range of from about 0.1% to about30% based on total weight of deposited equivalent metal and support. 12.The process of claim 1 wherein said alumina support has a surface areagreater than about 100 square meters per gram of support and a hydroxylcontent of at least 1 millimole per gram of support.
 13. The process ofclaim 12 wherein said impregnated support is heat-treated at atemperature of about 800° F.
 14. The process of claim 12 wherein saidheat-treated impregnated support is activated by contacting same with anorganometallic compound comprising aluminum triethyl and wherein theactivated supported metal complex is treated in the presence of hydrogenat a temperature of at least about 400° F.
 15. The process of claim 14wherein the aluminum triethyl is present in a paraffinic diluent in aconcentration of about 20 wt. % aluminum triethyl in the diluent. 16.The process of claim 1 wherein said impregnated support is heat-treatedat a temperature ranging between about 600° and 1500° F. in order toremove liquid and adsorbed oxygen therefrom.